Giải thích các bước giải:
`1/(x^2+4x+3` + `1/(x^2 + 8x + 15` + `1/(x^2 +12x +35) =1/9`
`<=>` `1/((x+1)(x+3)) + 1/((x+3)(x+5))+ 1/((x+5)(x+7)) = 1/9`
`<=>` `1/2(1/(x+1) - 1/(x+3 ))+1/2(1/(x+3) - 1/(x+5 ))+1/2 (1/(x+5) - 1/(x+7)) = 1/9`
`<=>` `1/2(1/(x+1) - 1/(x+7)) = 1/9`
`<=>` `1/2((x+7-x-1)/((x+1)(x+7))) =1/9`
`<=>` `3/((x+1)(x+3)) = 1/9`
`<=>` `(x+1)(x+7) = 27`
`<=>` `x^2 + 7x +x +7 -27 = 0`
`<=>` `x^2 +8x -20 = 0`
`<=>` `(x-2)(x+10)=0`
`<=>`\(\left[ \begin{array}{l}x=x-2\\x=x+10\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2\\x=-10\end{array} \right.\)
≈Học tốt≈
